steamcompmgr: fix another coredump-at-exit

src/backend.cpp

@@ -16,34 +16,34 @@ namespace gamescope
     // IBackend
     /////////////
 
-    static IBackend *s_pBackend = nullptr;
+    static std::atomic<IBackend*> s_pBackend = nullptr;
 
     IBackend *IBackend::Get()
     {
         return s_pBackend;
     }
-
+
+
     bool IBackend::Set( IBackend *pBackend )
     {
-        if ( s_pBackend )
-        {
-            delete s_pBackend;
-            s_pBackend = nullptr;
-        }
+    		//FIXME: calling the backend's destructor sometimes hangs gamescope for wayland backend
+    		//if ( s_pBackend ) {
+    		//	std::destroy_at(GetBackend());
+    		//}
 
         if ( pBackend )
         {
             s_pBackend = pBackend;
-            if ( !s_pBackend->Init() )
+            if ( !GetBackend()->Init() )
             {
-                delete s_pBackend;
-                s_pBackend = nullptr;
+								s_pBackend = nullptr;
                 return false;
             }
         }
 
         return true;
     }
+
 
     /////////////////
     // CBaseBackendFb
@@ -184,4 +184,4 @@ namespace gamescope
 
         GetBackend()->DumpDebugInfo();
     });
-}
+}

src/steamcompmgr.cpp

@@ -5896,8 +5896,25 @@ error(Display *dpy, XErrorEvent *ev)
 }
 
 [[noreturn]] static void
-steamcompmgr_exit(void)
+steamcompmgr_exit(std::optional<std::unique_lock<std::mutex>> lock = std::nullopt)
 {
+
+  // Need to clear all the vk_lutxd references (which can be tied to backend-allocated memory)
+  // for the colormgmt globals/statics, to avoid coredump at exit from within the colormgmt exit-time destructors:
+	for (auto& colorMgmtArr : 
+			{
+				std::ref(g_ColorMgmtLuts),
+				std::ref(g_ColorMgmtLutsOverride),
+				std::ref(g_ScreenshotColorMgmtLuts),
+				std::ref(g_ScreenshotColorMgmtLutsHDR)
+			})
+	{
+		for (auto& colorMgmt : colorMgmtArr.get())
+		{
+			colorMgmt.gamescope_color_mgmt_luts::~gamescope_color_mgmt_luts(); //dtor call also calls all the subobjects' dtors
+		}
+	}
+
 	g_ImageWaiter.Shutdown();
 
 	// Clean up any commits.
@@ -5922,21 +5939,21 @@ steamcompmgr_exit(void)
 	{
 		g_ColorMgmt.pending.appHDRMetadata = nullptr;
 		g_ColorMgmt.current.appHDRMetadata = nullptr;
-
 		s_scRGB709To2020Matrix = nullptr;
 		for (int i = 0; i < gamescope::GAMESCOPE_SCREEN_TYPE_COUNT; i++)
 		{
 			s_MuraCorrectionImage[i] = nullptr;
 			s_MuraCTMBlob[i] = nullptr;
 		}
 	}
-
+		if (lock)
+			lock->unlock();
     gamescope::IBackend::Set( nullptr );
 
     wlserver_lock();
     wlserver_shutdown();
     wlserver_unlock(false);
-
+	
 	pthread_exit(NULL);
 }
 
@@ -8042,7 +8059,7 @@ steamcompmgr_main(int argc, char **argv)
 		vblank = false;
 	}
 
-	steamcompmgr_exit();
+	steamcompmgr_exit(std::optional<std::unique_lock<std::mutex>> {std::in_place_t{}, std::move(xwayland_server_guard)} );
 }
 
 void steamcompmgr_send_frame_done_to_focus_window()